The inventive embodiments have application, in particular, to vehicles that have at least one lifting axle that can be lowered and raised in a controllable fashion, at least one steered axle that can be locked and unlocked in a controllable fashion, or both types of such vehicle axles. As used herein, an axle is understood to be a single vehicle axle or a multi-axle unit that is customary, in particular, in utility vehicles and that can have, for example, two or three axles arranged in the immediate vicinity of one another. The term lifting axle is used herein to refer to a vehicle axle that can be raised from the road surface by means of, for example, a rubber bellows that can be filled with compressed air, or lowered onto the road surface. A steered axle is understood to be, for example, a freely running, self-steering or steered axle that is positively steered by an external mechanism. In particular, in the case of utility vehicles, for example utility vehicle trailers, such steered axles are provided with a locking mechanism, with the result that, when necessary, the steered axle is locked in a straight-ahead travel position and can therefore be secured in position. DE 10 2008 031 089 A1 proposes, for example, locking such a steered axle of a trailer during reversing and also maintaining the lock during slow forward travel. DE 10 2008 054 328 A1 proposes automatically raising or lowering a lifting axle as a function of the axle load of another vehicle axle that is not embodied as a lifting axle. In addition, in the case of reversing, the lifting axle can automatically be raised in order to make the vehicle more maneuverable.
The foregoing proposals relate, in particular, to requirements and regulations in Europe. However, other countries, for example Canada, have regulations aimed at protecting roads and bridges against excessive and unnecessary wear caused by vehicles, particularly heavy lorries. In Canada, what are referred to as SPIF (Safe, Productive and Infrastructure Friendly) regulations require that multi-axle utility vehicles be equipped as far as possible with lifting axles and steered axles; in particular, combined axles, i.e., lifting steered axles, are to be provided.